Obesity is a common condition and major public health problem in developed nations including the United States. As of 2009, more than two thirds of American adults, approximately 127 million people, were either overweight or obese. Data suggest that 300,000 Americans die prematurely from obesity-related complications each year. Many children in the United States are also either overweight or obese. Hence, the overall number of overweight Americans is expected to rise in the future. It has been estimated that obesity costs the United States approximately $100 billion annually in direct and indirect health care expenses and in lost productivity. This trend is also apparent in many other developed nations.
For adults, the body mass index (BMI) is used to determine if one is overweight or obese. A person's BMI is calculated by multiplying body weight in pounds by 703 and then dividing the total by height in inches squared. A person's BMI is expressed as kilograms per meter squared. An adult is considered overweight if his or her BMI is between 25 and 30 kg/m2. Obesity is defined as possessing a BMI between 30 and 40 kg/m2. A BMI greater than 30 kg/m2 is associated with significant co-morbidities. Morbid obesity is defined as possessing either a body weight more than 100 pounds greater than ideal or a BMI greater than 40 kg/m2. Approximately 5% of the U.S. population meets at least one of the criteria for morbid obesity. Morbid obesity is associated with many diseases and disorders including, for example: diabetes; hypertension; heart attack; stroke; dyslipidemia; sleep apnea; pickwickian syndrome; asthma; lower back and disc disease; weight-bearing osteoarthritis of the hips, knees, ankles and feet; thrombophlebitis and pulmonary emboli; intertriginous dermatitis; urinary stress incontinence; gastroesophageal reflux disease (GERD); gallstones; and, sclerosis and carcinoma of the liver. In women, infertility, cancer of the uterus, and cancer of the breast are additionally associated with morbid obesity. Taken together, the diseases associated with morbid obesity markedly reduce the odds of attaining an average lifespan. The sequelae raise annual mortality rates in affected people by a factor of 10 or more.
Current treatments for obesity include diet, exercise, behavioral treatments, medications, surgery (open and laparoscopic), and endoscopic devices. New drug treatments for obesity are currently being evaluated in clinical trials. However, a high efficacy pharmaceutical treatment has not yet been developed. Further, short-term and long-term side effects of current pharmaceutical treatments often concern consumers, pharmaceutical providers, and/or their insurers. Generally, diet or drug therapy programs have been consistently disappointing, failing to bring about significant, sustained weight loss in the majority of morbidly obese people.
Currently, most operations used to treat morbid obesity include gastric restrictive procedures, involving the creation of a small (e.g., 15-35 ml) upper gastric pouch that drains through a small outlet (e.g., 0.75-1.2 cm), setting in motion the body's satiety mechanism. About 15% of operations used to treat morbid obesity performed in the United States involve combining a gastric restrictive procedure with a malabsorptive procedure. Typical malabsorptive procedures divide small intestinal flow into a biliary-pancreatic conduit and a food conduit. Potential long-term side effects associated with abdominal surgical procedures include herniation and small bowel obstruction. In addition, long-term problems specific to bariatric procedures also include gastric outlet obstruction, marginal ulceration, protein malnutrition, and vitamin deficiency.
Other surgical strategies for treating obesity include endoscopic procedures, many of which are still in development. Endoscopic procedures and devices to produce gastric pouch and gastrojejunal anastomosis are used to replicate laparoscopic procedures. Endoscopically placed gastric balloons restrict gastric volume and result in satiety with smaller meals. For example, U.S. Pat. No. 7,172,613, assigned to Districlass Medical SA, describes “An intragastric device inserted by endoscopic path into a patient's stomach. The device includes a balloon or envelope having a specific nominal volume. The balloon is sealingly connected to connecting elements consisting of a disc forming a support base for the balloon against an inner wall of the stomach. The device also includes a flexible tube or catheter for connecting the balloon to a filling device and catching element integral with the tube or catheter. The connection elements enable a doctor to set and/or remove the balloon and to fix, either inside the patient's body, or subcutaneously the filling device and to be able to bring the balloon or envelope to its predetermined nominal volume.”
The silicon intragastric balloon (IGB) has been developed as a temporary aid to achieve weight loss specifically for people who weigh 40% or more of their ideal weight and who have had unsatisfactory results in their treatment of obesity, despite being cared for by a multidisciplinary team. This treatment is also indicated for morbidly obese patients who have a high morbidity and mortality risk for surgery. The placement and removal of the IGB is an endoscopic procedure and the balloon is designed to float freely inside the stomach. The IGB technique reduces the volume of the stomach and leads to a premature feeling of satiety. However, use of IGBs did not show convincing evidence of a greater weight loss. The relative risks for minor complications, for example, gastric ulcers and erosions, were significantly raised. All inflatable IGB devices suffer from the problem of deterioration of the balloon over time. This deterioration can result in deflation with loss of efficacy and complications such as small bowel obstruction secondary to balloon migration. Due to loss of efficacy over time, IGB devices are recommended only for short (<6 month) durations. In addition, rapid inflation of the balloon poses the risk of esophageal or gastric perforations, both of which are surgical emergencies. Deaths have been reported in patients using IGB treatment.
Endoscopic procedures are also used to deploy mesh structures into the stomach in an effort to occupy stomach volume and create the artificial sensation of being full. For example, United States Patent Application Number 2007098039, assigned to Wilson-Cook Medical, Inc., describes “An intragastric device generally comprises a strip digestive-resistant mesh material that is operable between a first configuration and a second configuration. The first configuration is sufficiently small to permit introduction of the digestive-resistant mesh material into a gastric lumen of the mammal. The second configuration is sufficiently large to prevent the digestive-resistant mesh material from passing through the mammal's pylorus, thereby permitting the mesh member to act as an artificial bezoar.”
Although endoscopically placed balloon structures can be effective, they are not without their associated risks and complications. Mesh structures are effective in occupying available gastric volume but they do not address gastric emptying. Migration and small bowel obstruction from such devices continue to remain a significant problem. Therefore, a need exists for an intragastric device to treat obesity that combines the benefits obtained through reducing stomach volume and slowing gastric emptying while remaining relatively safe. This device should limit side effects and be able to be deployed and removed in a non-invasive manner with relative ease. In addition, this new device should have the option of further treating obesity by including the benefits obtained by malabsorptive diversion procedures. The addition of this optional benefit would make the device effective in treating not only obesity, but type II diabetes as well.